Hundreds, or even thousands, of drunk driving convictions could be overturned because the San Francisco Police Department has not tested its breathalyzers, officials said Monday. For at least six years, the police officers in charge of testing the 20 breathalyzers used by the Police Department did not carry out any tests on the equipment. Officers instead filled the test forms with numbers that matched the control sample, said Public Defender Jeff Adachi, throwing countless DUI convictions into doubt.